Lifting device



C. L. TRAPP LIFTING DEVICE July 16, 1929.

Filed July 9, 1928 Ch qrl es L. Tfa o o awvem io'o Patented July. 16,1929.

UNITED STATES I'PATENT OFFICE.

CHARLES L. TBAPP, 0F OMAHA, NEBRASKA, ASSIGNOR TO GLOBE MACHINERY & SUP-IE'LY COMPANY, OF DES MOINES, IOWA, A CORFORATION.

LIFTING nnvrcn,

Application filed July. 9,

My invention relates to that class of lifting devices, called pneumaticand hydraulic, which are commonly employed. for raising automobiles,platforms or other heavy objects, from lower to higher positions, andwhich individually comprise a container or reservoir for oil orlikerigid fluid, means for forcing-air or other elastic'fluid into thecontainer, a casing, or cylinder,connected with thecontainer, and apiston which is driven by v oil forced from the container into thecasing by air pressure. It is the main object of .the

invention to avoid, in devices of this descrip tion, allleakage of oilbetween the oil container and the casing; to prevent the siphonageof oilfrom the reservoir into the casing; to facilitate the removal of oilfrom the reservoir, as occasion may require; and to attain compactnessand simplicity of construction. T o accomplish these results, Iincorporate in my improved lifting device, as parts thereof, a casingwhich may be integrally united with he top of the oil reservoir, anintercommu- "nicating oil pipe-between the casing and the interior ofthe .oil reservoir, and asupply and discharge oil pipe extending fromoutside into the interior of the oil reservoir.

In said drawings, which illustrate the best manner in which I havecontemplated applying the principles of the invention, Fig. 1 is a planview of a lifting device which is constructed in accordance with theseprinciples. Fig. 2 is an axial section on the section line of Fig. 1.-Fig. 3 is an axial section of the same on the same section line, butwith the piston in a lifted position.

In these drawings the oil reservoir, which is a closed metallic tank ofgeneral cylin dri cal form, is denoted by the numeral 1. The

cylindrical casing 2 iswelded to the head 3 of this reservoir, and isthereby united with the tank coaxially, immediately, integrally, and ina manner to preclude leakage. This ca sing has at the top an annularheadl, which is held in place thereon by the screw studs 5. The piston,which is coaxial with the casing, comprises the hollow cylindrical rod,or stem 7, having the peripheral stop ring 20 and the head 8. The pistonproper 9 closes the lower end of the rod or stem 7 and fits snugly inthe cylinder 2 to travel therein. The packing 10, which contacts withthe inside of the cylinder 2 is clamped to the piston 9 by the screws 11and the follower 12. The packing is preferably of the cup leather typewith 1928. Serial No. 291,223.

the reservoir 1, I employ .any convenient means, including, andsufficiently represented by, the vertical pipe 13, which is joined tothe reservoir head 3 at the coupling 14. For

the purpose of supplying the oil reservoir with oil, and of emptying orrefilling the same,

as occasion or convenience may require, the vertical oil pipe 15 isjoined to the reservoir head 3 at the coupling 16 and extends upward tothe ground level or to any other desired height, where it is closed bythe removable screw cap 17. This pipe has a continuation 6, whichextends. within the reservoir from the coupling at 16 to a point nearthe bottom or floor of the reservoir. The open and vertical pipe 18,which is coupled to the middle of the reservoir head 3 at 19, and whichextendsnearly to the bottom of the reservoir, affords the onlyintercommunieation be tween the reservoir and the casing 2.

Operatively the reservoir may be supplied with oil 21 through the pipe15 and 6, which s afterward stopped by the cap 17, as shown in Fig. 2.By the pressure of air forced into the reservoir through pipe 13 oil isdriven continuously through pipe 18 into the casing, where it lifts thepiston from the position shown in Fig. 2, toward or to that shown -inFig. 3, where itis stopped by ring 20 in contact with head 1 of thecasing. On relief of the air pressure, as by the cock 22, the pistonwill return gradually to its original position. T he operative oilsupply may then be removed from the reservoir at pleasure through thepipe 6 and 15 by removing the cap 17 and by admitting air under pressurethrough pipe 13.

It will be noted that the piston rod or stem 7 is of smaller externaldiameter than the internal diameter of the cylinder 2 and that themember 4 serves as a guide for the piston rod.

The piston can be removed and oil supplied directly to the reservoirthrough the cylin- My lifting device is intended primarily for use inoil service stations for raising and rotating automobiles in orde toafford access to their under parts for oiling and greasing. The cylinderand reservoir are located in a suitable pit in the floor or in theground.

In some instances, there is arranged between a tank located above thelower end of the cylinder and the cylinder a pipe extenddesirable.

By placing the oil reservoir wholly below the cylinder and piston, Ihave provided a means whereby, if any leakage occurs, as for instance byseepage past the cup packing or otherwise, such oil will gravitate backinto the oil reservoir, and this result obviously cannot be attained bydevices of this character in which the oil reservoir is above some partof the piston or cylinder.

It will be observed that I have provided a very compact unit for thepurposes of sh1pping and installation. It is also to be noted that theoil is kept deep in the ground when the device is not in use. Thisavoids the danger of freezing 'or congealing it. It should also be notedthat the piston rod never contains oil and therefore that there isno oilabove the ground surface to congeal at any time in the operation of thedevice.

The piston rod being of smaller diameter than the interior of thecylindernever gathers any oil which might form a frozen film above thecylinder.

I claim as my invention 1. The combination of an upright cylinder, ahollow piston rod vertically movable in the cylinder and closed againstthe admission of oil at all times, a piston at the lower end of thepiston rod, a cup packing carried by the piston and having its flangeextended downwardly, an oil reservoir supported below the lower end ofthe cylinder and having a capacity slightly greater than that of thecyl-. inder below the piston when the piston is fully extended, a pipeleading from the bottom of the oil reservoir upwardly and capable ofdraining substantially all of the oil from the cylinder when the pistonis down and leaving an air chamber above the oil, and means forintroducing air under pressure to the top of the oil reservoir.

2. The combination of an upright cylinder, a piston vertically movablein the cylinder, a cup packing with its flange extended downwardlycarried by the piston, a hollow piston rod extended upwardly from thepiston, a guide for the upper portion of the piston rod, the hollowpiston rod being closed against the admission of oil at all times, anoil reservoir supported below the cylinder, a pipe extending from thebottom of the oil reservoir upwardly and communicating with the lowerend of the cylinder, and means for supplying air under pressure to thetop of the oil reservoir.

3. The combination of an upright cylinder, a piston vertically movablein the cylinder, 9. cup packing with its flange extendeddownwardly-carried by the piston, a piston rod extended upwardly fromthe piston, a guide for the upper portion of the piston rod, the pistonrod being closed against the admission of oil at all times, the pistonrod above the pistonand the interior of the cylinder being spaced apartso that a film of oil on the interior of the cylinder cannot betransmitted to the piston rod, an oil reservoir supported below thecylinder, a pipe extending from the bottom of the oil reservoir upwardlyand communicating with the lower end of the cylinder, and means forsupplying air under pressure to the top of the oil reservoir.

4:. The combinationot' an upright cylinder, a piston vertically movablein the cylinder, a cup packing with its flange extended downwardlycarried by the piston, a piston rod pressure to the top of the oilreservoir, and a stop device attached to the piston rod in said spacebetween the piston rod and the cylinder, to engage said guide.

5. In a lifting device, the combination of an upright cylinder, a pistonvertically reciprocable in the cylinder carrying a packing between itand the cylinder, a piston rod extending upwardly from the piston, anoil reservoir fixed to and forming a unitary structure with'the lowerend of the cylinder below the lowermost position of the movement of thepiston, a pipe extending from near the bottom of the oil reservoirupwardly and communicating with the lower end of the cylinder below thepiston, and means for supplying compressed air to the top of the oilreservoir.

. 6. The combination of an upright cylinder, a hollow piston rodvertically movable in the cylinder, 'a piston at the lower end of thepiston rod, apacking carried by the piston, an oil reservoir supportedbelow the lower end of the cylinder, a pipe leading from the bottom ofthe oil reservoir upwardlyand capable of draining substantially all ofthe 'oil from the cylinder when the piston is down, and means forintroducing air under pressure to the top of the oil reservoir.

Witness my signature at Omaha, Nebraska, June 30, 1928.

CHARLES L. TRAPP.

extended upwardly from the piston, a guide

